This invention relates to a cyclone separator and to a vacuum cleaner incorporating the same.
Vacuum cleaners all incorporate some form of dust separation apparatus to separate dirt and dust from an induced airflow. Historically, vacuum cleaners were provided with porous filter bags which filter and collect the dust. Once full, the dust bag can be discarded and replaced.
Nowadays it has become fashionable to provide vacuum cleaners with cyclonic separators which can simply be emptied without the need to purchase dust bags. Cyclonic separators also avoid the problem that dust bags can become clogged with dust if they are not changed regularly. A disadvantage of such cyclonic vacuum cleaners is that the dirt and dust collected at the bottom of the cyclone chamber can become re-entrained into the airflow if too much separated dirt and dust accumulates at the bottom of the chamber. Accordingly such cleaners have a limited capacity for separated dirt and dust and need to be emptied regularly.
Another disadvantage known to cyclonic vacuum cleaners is that the separated dirt and dust is simply emptied by removing the collection chamber from the cleaner and opening a flap or turning the chamber upside-down. The dirt and dust then falls under gravity into a refuse receptacle. This process is both messy and unhygienic.
Various solutions to the above mentioned problems have been proposed. DE3825773 discloses a vacuum cleaner comprising a cyclonic separation chamber in which dirt and dust separated from the airflow collects in the base of the cyclonic separation chamber and is then conveyed into a detachable dirt receptacle by a horizontally-disposed auger driven by an electric motor.
DE3717333 discloses a cyclonic vacuum cleaner separator incorporating a horizontal auger at the base of the separation chamber, whereby the auger drives the separated dirt into a cylindrical compaction chamber closed at its downstream end by a spring-loaded flap. The spring-loaded flap is forced open by the accumulated compacted dirt, whereupon cakes of dirt are ejected into a container, typically a bag, for disposal. A problem with this cleaner is that fibrous matter such as fluff and hair is not drawn into the auger with the result that it accumulates in the separation chamber and affects the cyclonic separation action and eventually causes a blockage.
EP1023864 discloses an upright cyclonic vacuum cleaner having a separator unit with a low-efficiency cyclonic separation chamber providing the first stage of separation. Partly-cleaned air exits the cyclone chamber through an axially-orientated cylindrical perforated pre-filter, within which is located a cylindrical pleated high-efficiency filter providing a second filtration stage. The pre-filter can be rotated about its axis by a manually-operated handle, and has on its external surface a helical ramp arranged to act as an auger. The interior of the pre-filter has a pair of radially-inward projecting resilient ribs which engage the pleats of the stage-2 filter. Thus, when the pre-filter is rotated, following use of the cleaner, or during emptying through a pivoted base flap, both the pre-filter and the stage-2 filter are vibrated due to contact of the ribs with the pleats of the stage-2 filter. Accumulated fine dust is thus shaken off their surfaces. At the same time, the helical ramp on the external surface of the pre-filter tends to propel accumulated coarse dirt downwards in the cyclone chamber, thus compacting the dirt at the base of the chamber.